1. Field
The disclosed aspects relate to wireless communication devices, and more particularly, to systems, methods and apparatus that provide for adjusting the Quality of Service (QoS) related to location determination in wireless communication devices and, in one embodiment, lowering the QoS after an unsuccessful location determination.
2. Background
Wireless communication devices, such as cellular telephones, portable computers and the like, have rapidly gained in popularity over the past decade. These devices are increasingly becoming multifaceted devices capable of providing a wide-range of functions. For example, today's cellular telephone may also embody computing capabilities, Internet access, electronic mail, text messaging, digital photographic capability, an audio/MP3 player, video gaming capabilities, video broadcast reception capabilities and the like.
In addition to the myriad of functions listed, mobile communication devices may be equipped with location determination devices and routines, such as Global Positioning System (GPS) sensors and routines or the like, that provide for the device to determine their respective geographic position at any point in time. Location information is most commonly used in navigation systems, which track geographic position with respect to a mapped destination, and may be incorporated with wireless communication devices, such as cellular telephones or the like. However, use of positioning information in wireless communication devices is not limited to navigational systems. Other applications may also rely on location information. For example, performance tracking systems, which may reside internally at the wireless device or externally at the network level, benefit from knowing the location at which a performance problem occurs, such as the location of a call drop, an out of service (OOS) occurrence or a call failure. Additionally, many other applications are relying on environmental characteristics of the device, such as the location of the device to modify or update the methodology of the application.
Currently various modes of operation exist for determining location. For example, GPS, Galileo, GLONASS (GLObal NAvigation Satellite System) or other satellite-based systems may rely on a Mobile Station-Based (MS-Based) mode, a Mobile Station-Assisted (MS-Assisted) mode, a Standalone mode or any other feasible mode currently known or known in the future. The various modes offer different methods for determining location. For example, in MS-Based mode the wireless device obtains information related to the location of satellites from a network Location Determining Entity (PDE) and then performs the location determination calculation at the wireless communication device. The satellite location information is commonly referred to as Ephemeris data and Almanac data. Almanac data is course orbital parameters for all the satellites in the system and is considered valid for up to several months. Ephemeris data by comparison is very precise orbital and clock correction for each satellite and is considered valid for about 30 minutes. Thus, in MS-Based mode a wireless device may, but is not always required to, obtain the information from the PDE depending on the currentness of the satellite information.
In MS-Assisted mode the wireless device relies on the PDE to perform the location and, as such, is required to communicate with the PDE each time a location determination is performed. Therefore, by comparison, while MS-based mode requires a wireless signal to communicate with the PDE for some of the location determinations, MS-assisted mode requires a wireless signal to communicate with the PDE for all of the location determinations.
In contrast, in Standalone mode all the functions are carried out at the wireless device and, since no PDE satellite information is required, no wireless signal is required. However, Standalone mode requires that the wireless device receive signals from at least four of the GPS satellites, while MS-Assisted mode can calculate a fix with few, and in some instances not any, satellites. Thus, Standalone mode has a high failure rate when attempts are made indoors, while the MS-Assisted mode has much higher availability indoors.
In current practice, the applicable location determination mode is defined by the application or is chosen at the initialization/start-up stage. Thus, the chosen mode applies to a location determinations request even if the mode may not be the best mode for all scenarios. Various conditions may exist throughout the executing duration of an application that are relevant to the effectiveness of the chosen mode. For example, MS-Assisted mode requires a wireless signal, such as a CDMA (Code Division Multiple Access) signal or GSM (Global System for Mobile) signal and, therefore, if the chosen mode is MS-Assisted, location determination will not occur if a wireless connection is not available. Other conditions that affect the performance of location determination modes are the current environment of the device, battery life, voice call state, data call state, the currentness of the satellite information and the like.
In addition to relying on satellites to determine location, MS-Assisted mode will record the current network parameters to obtain a network-based location determination. Network parameters and associated network-based location determination refers to any terrestrial-based parameters and terrestrial-based location determination. Examples of network-based methods used to determine wireless device location include, but are not limited to, Advanced Forward Link Trilateration (AFLT), Enhanced Forward Link Trilateration (EFLT), Enhanced Observed Time Difference (EOTD), Observed Time Difference of Arrival (OTDOA) and the like. AFLT is the method generally associated with MS-Assisted mode and is a wireless device-based location determination that uses a phase offset technique to determine location. To determine location, the wireless device takes measurements of signals from nearby cellular base stations and reports the pilot phase measurements back to the network, which are then used to trilaterate an approximate location of the wireless device. Characteristically, network-based methods tend to be less accurate than satellite-based location fixes.
As previously noted, satellite-based location determination methods generally require information from at least three satellites. Thus, the wireless device must be located in an area capable of receiving information from multiple satellites. Indoor locations, dense urban areas, and certain natural structures, like canyons and the like, may offer challenges to accurate and time efficient satellite fixes. In addition, other limitations such as erratic ionospheric conditions, noise at the wireless device level and the like may prohibit obtaining a satellite-based fix or impact the accuracy of the satellite-based fix. In these instances, it may be desirable to rely on network-based parameters to obtain a network-based location determination.
In the same regard, certain wireless device applications that require location information may favor a faster location determination fix even if some degree of accuracy is sacrificed. For example, in the mobile environment, applications that track the occurrence of a call event, such as a call drop, a call failure or the like, may be more concerned with determining the location at the moment the call event occurs as opposed to determining a more accurate location at a point in time removed from the call event. This is especially evident in the scenario in which the call event occurs in a moving vehicle; the call event tracking application desires an immediate location determination fix, regardless of accuracy, to be able to associate location with the call event. If the call event tracking application has to wait a certain amount of time for the location determination fix, the resulting location may be a significant distance from the location at which the call event occurred, depending on the speed of the vehicle. In this instance, the application may place a higher priority on speed at which a location is determined as opposed to the precise accuracy of the determined location.
Therefore, a need exists to provide systems and methods for accelerating location determination in wireless communication devices. As such, the desired systems and methods may provide more efficient location fixes, in terms of time to process the location fix. Such systems and method will greatly benefit applications that place a higher priority on the speed at which a fix is obtained as opposed to the accuracy of the fix. In addition, the desired systems and methods should take into account conditions that exist at the point in time when a location determination is made to insure the likelihood of location determination success and further expedite the location determination process.